Ultracytochemical localization of NAD(P)H oxidase activity in the human placenta.

Ultracytochemical localization of NAD(P)H oxidase activity was demonstrated in the human term placenta by the cerium method. The activity of this enzyme was also compared to those of other oxygen-intermediates-metabolizing enzymes, such as xanthine oxidase, catalase, peroxidase and superoxide dismutase. NAD(P)H oxidase activity was exclusively confined to the apical microvillous membrane of the syncytiotrophoblast. Other enzymes studied showed no activity. We discuss the possibility that NAD(P)H oxidase might play a role in transferring substances between mother and fetus and that this enzyme might modulate placental H2O2 production.